You could simply build the script your self(this is just the basics):
HTML Code:
<script type="text/javascript">
var currentTime = new Date()
var month = currentTime.getMonth() + 1
var day = currentTime.getDate()
var year = currentTime.getFullYear()
document.write(month + "/" + day + "/" + year)
</script>
Then you just need to define when to end and every time the page refreshed the count down will get closer.